Message ID | 20200730221737.51569-1-cengiz@kernel.wtf (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | [v2] staging: atomisp: move null check to earlier point | expand |
On Fri, Jul 31, 2020 at 01:17:38AM +0300, Cengiz Can wrote: > `find_gmin_subdev` function that returns a pointer to `struct func() are referred with name followed by parentheses. > gmin_subdev` can return NULL. > In `gmin_v2p8_ctrl` there's a call to this function but the possibility > of a NULL was not checked before its being dereferenced. ie: '. ie:' -> ', i.e.:' > ``` Instead just shift right by two spaces. > /* Acquired here --------v */ > struct gmin_subdev *gs = find_gmin_subdev(subdev); > > /* v------Dereferenced here */ > if (gs->v2p8_gpio >= 0) { > ... > } > ``` Drop this as per above comment. > To avoid the issue, null check has been moved to an earlier point > and return semantics has been changed to reflect this exception. > Please do note that this change introduces a new return value to > `gmin_v2p8_ctrl`. This rather should explain better the semantics change, e.g. "Now the function() refuses to take NULL argument and returns an error. We also WARN() for sake of the debugging." > [NEW] - raise a WARN and return -ENODEV if there are no subdevices. > - return result of `gpio_request` or `gpio_direction_output`. > - return 0 if GPIO is ON. > - return results of `regulator_enable` or `regulator_disable`. > - according to PMIC type, return result of `axp_regulator_set` > or `gmin_i2c_write`. > - return -EINVAL if unknown PMIC type. This has to go after cutter '---' line below. > Caught-by: Coverity Static Analyzer CID 1465536 Reported-by: And as discussed previously, Suggested-by: Mauro ... > Signed-off-by: Cengiz Can <cengiz@kernel.wtf> The code looks good enough (WARN() will probably go away when driver gains better quality).
diff --git a/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c b/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c index 0df46a1af5f0..1ad0246764a6 100644 --- a/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c +++ b/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c @@ -871,6 +871,9 @@ static int gmin_v2p8_ctrl(struct v4l2_subdev *subdev, int on) int ret; int value; + if (WARN_ON(!gs)) + return -ENODEV; + if (gs->v2p8_gpio >= 0) { pr_info("atomisp_gmin_platform: 2.8v power on GPIO %d\n", gs->v2p8_gpio); @@ -881,7 +884,7 @@ static int gmin_v2p8_ctrl(struct v4l2_subdev *subdev, int on) pr_err("V2P8 GPIO initialization failed\n"); } - if (!gs || gs->v2p8_on == on) + if (gs->v2p8_on == on) return 0; gs->v2p8_on = on;
`find_gmin_subdev` function that returns a pointer to `struct gmin_subdev` can return NULL. In `gmin_v2p8_ctrl` there's a call to this function but the possibility of a NULL was not checked before its being dereferenced. ie: ``` /* Acquired here --------v */ struct gmin_subdev *gs = find_gmin_subdev(subdev); /* v------Dereferenced here */ if (gs->v2p8_gpio >= 0) { ... } ``` To avoid the issue, null check has been moved to an earlier point and return semantics has been changed to reflect this exception. Please do note that this change introduces a new return value to `gmin_v2p8_ctrl`. [NEW] - raise a WARN and return -ENODEV if there are no subdevices. - return result of `gpio_request` or `gpio_direction_output`. - return 0 if GPIO is ON. - return results of `regulator_enable` or `regulator_disable`. - according to PMIC type, return result of `axp_regulator_set` or `gmin_i2c_write`. - return -EINVAL if unknown PMIC type. Caught-by: Coverity Static Analyzer CID 1465536 Signed-off-by: Cengiz Can <cengiz@kernel.wtf> --- drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)